Watch iTunes movie on Amazon Fire TV via Plex

For people who have tried numerous ways to stream video and music, Amazon Fire TV with Plex absolutely should not be ignored.

As Amazon's answer to the Apple TV, Amazon Fire TV comes with tons of online media content. For anyone who wants to stream local movie library to Fire TV, Plex for Amazon Fire TV is widely used for its outstanding ability to stream nearly all kinds of videos, except DRM protected movies.

DRM protection is used by Apple to put on all iTunes downloaded videos. It aims to prevent video spreading on non-ios devices. So what if you purchased some video in iTunes Store and want to stream to Fire TV? How to remove the DRM protection?